Research Arising from CSIRO/AMIRA Regolith Geochemistry
© CSIRO Exploration and Mining
In 1987, CSIRO Division of Exploration Geoscience (now CSIRO Division
of Exploration and Mining) commenced a series of multi-client research
projects in regolith geology and geochemistry which were sponsored
by companies in the Australian mining industry, through the Australian
Mineral Industries Research Association Limited (AMIRA). The initial
research program, "Exploration for concealed gold deposits,
Yilgarn Block, Western Australia" (1987-1993) had the aim of
developing improved geological, geochemical and geophysical methods
for mineral exploration that would facilitate the location of blind,
buried or deeply weathered gold deposits.
The program included the following projects:
P240: Laterite geochemistry for detecting concealed mineral deposits
Leader: Dr R.E. Smith
Its scope was development of methods for sampling and interpretation
of multi-element laterite geochemistry data and application of multi-element
techniques to gold and polymetallic mineral exploration in weathered
terrain. The project emphasised viewing laterite geochemical dispersion
patterns in their regolith-landform context at local and district
scales. It was supported by 30 companies.
P241: Gold and associated elements in the regolith - dispersion
processes and implications for exploration (1987-1991)
Leader: Dr C.R.M. Butt
The project investigated the distribution of ore and indicator
elements in the regolith. It included studies of the mineralogical
and geochemical characteristics of weathered ore deposits and wall
rocks, and the chemical controls on element dispersion and concentration
during regolith evolution. This was to increase the effectiveness
of geochemical exploration in weathered terrain through improved
understanding of weathering processes. It was supported by 26 companies.
These projects represented "an opportunity for the mineral
industry to participate in a multi-disciplinary program of geoscience
research aimed at developing new geological, geochemical and geophysical
methods for exploration in deeply weathered Archaean terrains".
This initiative recognised the unique opportunities, created by
exploration and open-cut mining, to conduct detailed studies of
the weathered zone, with particular emphasis on the near-surface
expression of gold mineralisation. The skills of existing and specially
recruited research staff from the Floreat Park and North Ryde laboratories
(of the then Divisions of Minerals and Geochemistry, and Mineral
Physics and Mineralogy, subsequently Exploration Geoscience and
later Exploration and Mining) were integrated to form a task force
with expertise in geology, mineralogy, geochemistry and geophysics.
Several staff participated in more than one project. Following completion
of the original projects, two continuation projects were developed.
P240A: Geochemical exploration in complex lateritic environments
of the Yilgarn Craton, Western Australia
Leaders: Drs R.E. Smith and R.R. Anand
The approach of viewing geochemical dispersion within a well-controlled
and well-understood regolith-landform and bedrock framework at detailed
and district scales continued. In this extension, focus was particularly
on areas of transported cover and on more complex lateritic environments
typified by the Kalgoorlie regional study. This was supported by
P241A: Gold and associated elements in the regolith.
The significance of gold mobilisation under present-day conditions,
particularly the important relationship with pedogenic carbonate,
was investigated further. In addition, attention was focussed on
the recognition of primary lithologies from their weathered equivalents.
This project was supported by 14 companies.
Although the confidentiality periods of the research reports have
expired, the last in December 1994, they have not been made public
until now. Publishing the reports through the CRC LEME Open File
Report Series is seen as an appropriate means of doing this. By
making available the results of the research and the authors' interpretations,
it is hoped that the reports will provide source data for future
research and be useful for teaching. CRC LEME acknowledges the Australian
Mineral Industries Research Association and CSIRO Division of Exploration
and Mining for authorisation to publish these reports. It is intended
that publication of the reports will be a substantial additional
factor in transferring technology to aid the Australian Mineral